1. Technical Field of the Invention
The present invention relates to RF shielding applications, and more particularly, to RF shield cans having over molded gaskets.
2. Description of Related Art
In electronic application such as cellular telephones, RFI/EMI shielding is necessary to protect and shield sensitive components from interference generated by other components and external sources. Important design considerations of RF shielding involve minimizing the required board area for the RF shield. This involves consideration of the RF shield footprint, placement accuracy of the RF shield and allowance for component clearances.
Previous methods of connecting RF Shields have included directly soldering the metal shield can to a printed circuit board. While soldering provides an excellent ground contact between the shield and the printed circuit board, this method produces a permanently attached shield can that cannot be readily removed if post-solder assembly or testing is required of the protected circuits. Another method of RF shielding involves the use of electrically conductive adhesive as a bond between the shield and the printed circuit board. However, this approach requires a larger footprint on the printed circuit board to allow an adequate surface area for the adhesive bond.
A final method of shield can connection utilizes a dispensed gasket applied to the edge of the RF shield. A dispensed gasket requires a considerably wider width than the can sidewall to allow for adequate bond surface and to compensate for variation in the position of the sidewall location. Current dispensing technology requires the gasket bead to overlap both sides of a thin sidewall to stabilize and harden properly. The gasket width must be further enlarged to accommodate sidewall positioning tolerances and dispensing process tolerances. This occupies a larger area on the printed circuit board, reducing the amount of available space for components.